AND TWELVE NEW SPECIES OF ROTIFERA OF THE ORDER BDELLOIDA. 373 
accepted. The number of known species belonging to this family is now so great that 
some subdivision of the genera would be desirable, even if those genera were natural. 
Many of the new species show the artificial character of the old genera, and render a 
revision imperative. 
I understand that a revision of the genera is now being prepared by Mr Bryce, who, 
from his long experience of the order, is so well qualified to do so. This being so, I 
shall here only amend the definitions of the genera Philodina and Callidina so as to 
render them more natural. The classification based upon the eyes having proved 
defective, other characters of a more reliable nature have been sought. The number of 
toes has been suggested by MiLNE* as a basis for classification. The mode of repro- 
duction was thought of. It was found that large groups of species agreeing in the 
number of toes, also agreed in the mode of reproduction. One or two exceptions, 
however, lessen the value of the mode of reproduction as a generic character, and it 
must be abandoned in the meantime. 
PHILODINA. 
Generic character.—Toes, four. MrItne’s suggestion is adopted, though it is 
recognised that the genus will have to be divided. Thus defined, the genus does not 
differ greatly from that of Enrensperc. All the species having eyes in the neck (ze. 
seated on the brain) are found, with one exception, to have four toes. The main result 
of the alteration will be the transfer to Phalodina of several species hitherto included in 
Callidina. 
CALLIDINA. 
Generic characters.—Toes, three ; or foot ending in a disc. Normally oviparous. 
This definition is simply provisional. It is unsatisfactory, in that it includes a 
character, viz., the mode of reproduction, which is not quite invariable. It is only by 
using this character that the genus Rotifer could be kept separate. 
As formerly distinguished by a single negative character, viz., the absence of eyes, 
the genus Callidina became the receptacle for all the homeless wanderers of the family, 
till it now includes a host of species, many of which have little affinity one with 
another. It is with this genus that a revision of the family will be mainly concerned. 
Four of the new species here described belong to that very natural section of the genus 
in which the food is moulded into pellets. Two have the discoid ‘symbiotic’ foot. 
This type of foot might be made the basis of a genus, were it not that it is in some 
cases impossible to determine whether there are separate toes or not. It is, moreover, 
suspected that the discoid foot may have been independently acquired by unrelated 
animals. 
* Proc. Phil. Soc. Glasgow, vol. xvii. p. 134, 1886. 
